The present invention relates to an RF coil (radio frequency coil), a magnetic resonance signal measuring apparatus and a magnetic resonance imaging apparatus, and more particularly, to an RF coil surrounding an imaging object in the proximity of the object, a magnetic resonance signal measuring apparatus using the RF coil and a magnetic resonance imaging apparatus using the magnetic resonance signal measuring apparatus.
In a magnetic resonance imaging (MRI) apparatus, an RF coil is provided in close proximity of imaging object, and a magnetic resonance signal is measured in a position as close as possible to an imaging position so as to improve SNR (signal-to-noise ratio) of the signal.
That is, to perform imaging on a head, a cervical spine (C spine) a thoracic spine (T spine), a lumbar spine (L spine) and the like, RF coils matched to the shapes and sizes of the imaging portions are used.
In head imaging, as a related portions are simultaneously subjected to imaging, it is preferable to use an integrated-type RF coil having an imaging range from a vertex to a neck. As the head and the neck having different diameters are connected in this portion, the diameter of RF coil is adjusted in accordance with the diameter of the head. Accordingly, regarding the neck, signal reception in good SNR cannot be made. Further, in this case, the RF coil must be formed avoiding a nose, the diameter of the coil is too large for the substantial diameter of the head. Accordingly, the SNR is not always high.
Further, in use of integrated type RF coil having an imaging range from the vertex to an upper T spine, if the diameter of the coil is fixed, it is adjusted in accordance with the diameter of the breast. Accordingly, signal reception in good SNR cannot be made regarding the head and neck.
It is therefore an object of the present invention to provide an RF coil for effective imaging on a head and a neck, a magnetic resonance signal measuring apparatus using the RF coil, and a magnetic resonance imaging apparatus using the magnetic resonance signal measuring apparatus.
Further, it is another object of the present invention to provide an RF coil for effective imaging from a vertex to an upper T spine, a magnetic resonance signal measuring apparatus using the RF coil, and a magnetic resonance imaging apparatus using the magnetic resonance signal measuring apparatus.
(1) In accordance with a first aspect of the invention, there is provided an RF coil comprising: a first coil loop surrounding a head of an imaging object approximately in a forehead and upper portions, divisible along a forward/backward direction of the imaging object; a second coil loop projecting from the imaging object approximately in a nose portion and surrounding the head of the imaging object, divisible along the forward/backward direction of the imaging object; and a third coil loop surrounding a neck of the imaging object, divisible along the forward/backward direction of the imaging object.
In the invention in this aspect, three types of coil loops having diameters respectively corresponding to the forehead portion, the nose portion and the neck are used, and the coils are divisible along the forward/backward direction of the imaging object. By this arrangement, the RF coil is matched to the forehead portion, the nose portion and the neck having different diameters and can accommodate these portions.
(2) In accordance with a second aspect of the invention, there is provided the RF coil according to (1), having a fourth coil loop, substantially orthogonal to respective said first coil loop and said second coil loop on both sides of the head of the imaging object, divisible along the forward/backward direction of the imaging object.
In the invention in this aspect, as coil loops are provided on both sides of the head, the RF coil can perform quadrature signal reception regarding the head.
(3) In accordance with a third aspect of the invention, there is provided the RF coil according (1) or (2), wherein said respective coil loops are respectively integrated by plastic molding on one side and the other side of said division.
In the invention in this aspect, as the respective coil loops are respectively integrated by plastic molding on one side and the other side of division, the imaging object can be easily inserted and removed.
(4) In accordance with a fourth aspect of the invention, there is provided the RF coil according to (3), wherein a front half by said division has openings in portions respectively corresponding to eyes and a jaw of the imaging object.
In the invention in this aspect, the sense of blockage of the imaging object can be mitigated by the openings in the portion corresponding to the eyes. Further, the opening in the portion corresponding to the jaw is formed to avoid hampering the jaw.
(5) In accordance with a fifth aspect of the invention, there is provided the RF coil according to (3) or (4), wherein the front half by said division is molded into a cage with said respective coil loops as its frame.
In the invention in this aspect, as the front half of the RF coil only has a frame, the sense of openness of the RF coil is increased.
(6) In accordance with a sixth aspect of the invention, there is provided The RF coil according to any one of (1) to (5), having a fifth coil loop, passing in front of a breast and in the rear of a back from shoulders of the imaging object, divisible along the forward/backward direction of the imaging object.
In the invention in this aspect, as the fifth coil loop is provided, the image sensing range can be extended to the upper T spine. (7) In accordance with a seventh aspect of the invention, there is provided the RF coil according to (6), wherein in said fifth coil loop, a distance between a part passing in front of said breast and a part passing in the rear of said back is adjustable.
In the invention in this aspect, as the interval between the front and rear parts of the fifth coil loop is adjustable, the coil can be adjusted in accordance with imaging objects having different breast circumferences. (8) In accordance with a eighth aspect of the invention, there is provided the RF coil according to (7), wherein the part passing in front of said breast has a hinge in a portion near the neck of the imaging object.
In the invention in this aspect, the interval can be easily adjusted by the hinge.
(9) In accordance with a ninth aspect of the invention, there is provided a magnetic resonance signal measuring apparatus comprising: a first coil loop surrounding a head of an imaging object approximately in forehead and upper portions, divisible along a forward/backward direction of the imaging object; a second coil loop projecting from the imaging object approximately in a nose portion and surrounding the head of the imaging object, divisible along the forward/backward direction of the imaging object; a third coil loop surrounding a neck of the imaging object, divisible along the forward/backward direction of the imaging object; and magnetic resonance signal measuring means connected to said respective coil loops.
In the invention in this aspect, three types of coil loops having diameters respectively corresponding to the forehead portion, the nose portion and the neck are used, and the coils are divisible along the forward/backward direction of the imaging object. By this arrangement, the RF coil is matched to the forehead portion, the nose portion and the neck having different diameters and can accommodate these parts, and by the RF coil, a magnetic resonance signal can be measured in good SNR.
(10) In accordance with a tenth aspect of the invention, there is provided is a magnetic resonance imaging apparatus comprising: magneto-static field formation means for forming a magneto-static field in space accommodating an imaging object; gradient magnetic field formation means for forming a gradient magnetic field in said space; high-frequency magnetic field formation means for forming a high-frequency magnetic field in said space; a first coil loop surrounding a head of the imaging object approximately in forehead and upper portions, divisible along a forward/backward direction of the imaging object; a second coil loop projecting from the imaging object approximately in a nose portion and surrounding the head of the imaging object, divisible along the forward/backward direction of the imaging object; a third coil loop surrounding a neck of the imaging object, divisible along the forward/backward direction of the imaging object; magnetic resonance signal measuring means connected to said respective coil loops; and image generation means for generating an image based on a magnetic resonance signal measured by said magnetic resonance signal measuring means.
In the invention in this aspect, three types of coil loops having diameters respectively corresponding to the forehead portion, the nose portion and the neck are used, and the coils are divisible along the forward/backward direction of the imaging object. By this arrangement, the RF coil is matched to the forehead portion, the nose portion and the neck having different diameters and can accommodate these parts. By this RF coil, a magnetic resonance signal can be measured in good SNR, and a high-quality image can be generated based on the measured signal.
According to the present invention, it is possible to realize an RF coil for effective imaging on a head and a neck, a magnetic resonance signal measuring apparatus using the RF coil, and a magnetic resonance imaging apparatus using the magnetic resonance signal measuring apparatus.
Further, it is possible to realize an RF coil for effective imaging from a vertex to an upper T spine, a magnetic resonance signal measuring apparatus using the RF coil, and a magnetic resonance imaging apparatus using the magnetic resonance signal measuring apparatus.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.